REEF AESTHETICS SURVEYS

This is a subjective attribute based on the observer's judgement and experience of the relative merits of a reef. This value judgement should incorporate coral cover, diversity of life forms, fish life, reef structure and general appeal. Observers should take care not to allow the present weather conditions to bias their judgement when assigning this category.

• Very poor
• Poor
• Average
• Good
• Very good
• Excellent

Dominant benthic form

When determining percentage cover of hard coral during a manta tow survey the observer should note if a particular benthic form dominates an area. The dominant benthic form categories used to describe a reef are:

• Hard coral - Scleractinia coral species
• Soft coral - Alcyonaria species
• Macro algae - Large, non-filamentous algae with a well-developed stems
• Coralline/turf algae - All forms of encrusting algae and filamentous turf algae
• Sand/Rubble - All unconsolidated substrate such as sand and broken fragments of coral and rock
• Sponge - Porifera species

Dominant hard coral genus

If hard coral is the dominant benthic form in a zone, then it is broadly categorised as Acropora or non-Acropora. If hard coral is not dominant, or there appears to be equal dominance of Acropora and non-Acropora, then it is classified as 'no one coral genus dominant'.

A. Acropora genus
C. A non-Acropora genus
N. No one coral genus dominant

Dominant hard coral form

There are eight coral life forms, which commonly dominate a reef slope. If there is no one dominant coral form, or if hard coral is not dominant, then it is recorded as 'no dominant form'. The coral forms are pictured in Figure 6 and are described below:

B. Branching - consist of arborescent branches of variable thickness that have a common base. They are typified by the staghorn corals such as Acropora grandis and formosa. Other branching species include Porites cylindrica and Seriatopora hystrix.

C. Corymbose - a growth form characteristic of Acropora where colonies are composed of horizontal branches and short to moderate vertical branchlets that terminate in a flat top, such as, A. tenuis, A.valenciennesi and A.cerialis.

D. Digitate - a growth form of Acropora where colonies are composed of short, non- anastomosing branches like the fingers of a hand eg., A. humilis and A. gemmifera.

E. Encrusting - have a prostrate, spreading growth form, that adheres to the substratum eg., Mycedium elephantotus, Lithophyllon edwardsi and many Montipora species.

F. Foliose - are erect, with a flattened, leaf-like growth form that may be folded and convoluted, often forming whorls. This form can sometimes be difficult to differentiate from encrusting corals, eg., Turbinaria mesentaria and Echinopora lamellosa.

M. Massive - have a similar shape in all directions (ie. spherical) and may form very large colonies, eg., Favia lizardensis, Diploastrea heliopora and many Porites species.

S. Submassive - are typically robust but have a wide morphological range and do not easily correspond to any other life form category. Many branching or massive corals may become submassive especially in high energy zones of the reef, eg., Acropora cuneata, Stylophora pistillata and Pocillopora meandrina which have a knobbed or bushlike appearance.

T. Tabulate - as their name suggests, tabulate corals have a tiered growth form consisting of horizontal, flattened plates, eg., A. hyacinthus and A. clathrata.

Live hard coral cover

Coral cover is determined from the median cover category estimate recorded by manta tow over the given reef zone. The categories are listed in Table 5.

Structural complexity

This is a subjective category designed to indicate the topography of the reef slope.

• Uniform - a consistent, featureless area of reef, such as reef pavement, vertical drop-offs, flat, sandy, back reef areas or an area of staghorn coral.
• Mixed - a variable reef slope that may be a solid edge interspersed with occasional grooves.
• Complex - a very diverse slope that may consist of "spur and grooves," caves, holes, overhangs or bommies.

T. gigas abundance

The giant clam (Tridacna gigas), is easily observed and identified while manta towing. The number of T. gigas is recorded for each manta tow in the 'other' column on the data sheet. These counts are totalled for the zone and given an abundance category. If clams are not counted then a note should be made in the 'other' column.

0. None
1. 1 - 10
2. 11 - 25
3. 25 - 50
4. > 50

Fish abundance

This attribute is an estimate of the total fish abundance over the zone. The categories are subjective and rely on the observer's perception and experience.

1. Low
2. Moderate
3. High
4. Very high

Coral bleaching

Coral bleaching looks similar to scars caused by COTS, as the corals appear brilliant white. A close inspection of bleached coral will reveal that the polyps are still visible, although colourless. Bleaching should be recorded only if it is unambiguous. It is recorded as a percent cover category (Table 5).

Figure 6. Dominant hard coral forms.

 

Branching	Corymbose
Digitate	Encrusting
Foliose	Massive
Submassive	Tabulate

 

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